Sand plays a crucial role in sustaining human civilization and Earth’s life. The ongoing production of sand is critically important for compensating for the Sun’s increasing luminosity. Six recent astrophysical studies establish the extraordinary degree of planetary fine-tuning that is needed for a planet to possess the required quantity of sand and continual production of sand to make advanced life on that planet possible.
Like the air we breathe, sand is taken for granted yet it is life-essential. It is everywhere and abundant. There are about as many grains of sand on Earth as there are stars in the universe.
Sand (or silica or silicon dioxide) exists on Earth in both the pure state (SiO2) and the silicates that comprise the continents. Industrially, it is used in making glass, ceramics, concrete, as filler for paint and rubber, and in preparing silicon carbide, fused quartz, and certain gels. Silica is found in many algae species, especially in the hard shells of diatoms, and in the stems of many vascular plants. It is essential for maintaining the texture and moisture retention of terrestrial soils that advanced plants require.
However, Earth did not start out with sand or silicates. It took strong, enduring plate tectonic activity and abundant liquid water at a specified temperature and pressure to gradually, chemically transform basalts into silicates. It took liquid water and plate tectonic activity on Earth at highly fine-tuned levels of abundance and stability to transform the planet from a water world into a realm where continents today cover 29 percent of Earth’s surface and oceans the other 71 percent. It took an efficient and globally active water cycle to establish silicate erosion whereby rain falling on exposed silicates acts as a catalyst to transform atmospheric carbon dioxide and continental silicates into sand and carbonates (both vital industrial and biological resources).
Without the efficient, continual water erosion of exposed silicates, Earth’s habitability cannot be sustained. The removal of carbon dioxide from Earth’s atmosphere via silicate erosion compensates for 80 percent of the Sun’s brightening. (All stable burning stars get brighter as they age.) This removal process ensures Earth’s surface temperature remains ideal for life. The other 20 percent compensation comes from the burial of once-living tissues by erosion and tectonics.
Six astrophysical research papers published from June to September 2012 establish that Earth may be unique in possessing a habitability window wide enough (3+ billion years) for possible advanced life.1 Only an Earth-sized planet with an extraordinarily unusual elemental abundance can sustain enduring plate tectonics. Only an Earth-like planet that loses virtually all of its water and atmosphere soon after its formation is capable of sufficiently enduring silicate erosion. Only a planet whose residual water and atmosphere remain at just-right levels, neither diminished nor augmented, can sustain advanced life.
Several ecological studies establish that key to maintaining that window wide enough is the existence of just-right life-forms in just-right abundances, locales, epochs, and diversities so that silica is recycled at just-right rates in just-right locations.2 Ecological studies have also discovered that certain harvesting practices disrupt Earth’s silica cycle.3 This finding seems to corroborate the idea that Earth’s life is fine-tuned to facilitate silica recycling.
Sand testifies to God’s handiwork. His hand is evident in shaping Earth’s formation and history and ensuring that the planet continuously possesses just-right geophysical processes operating at just-right rates, times, and places. This, combined with the creation of just-right life at just-right times and places, explains why we are blessed with such an abundance of the right kinds of sand so that human civilization can thrive.
1. Patrick A. Young, Kelley Liebst, and Michael Pagano, “The Impact of Stellar Abundance Variations on Stellar Habitable Zone Evolution,” Astrophysical Journal Letters 755 (August 20, 2012): L31; Matthew R. Mumpower, G. C. McLaughlin, and Rebecca Surman, “The Rare Earth Peak: An Overlooked r-Process Diagnostic,” Astrophysical Journal 752 (June 20, 2012): 117; A. Lenardic and J. W. Crowley, “On the Notion of Well-Defined Tectonic Regimes for Terrestrial Planets in This Solar System and Others,” Astrophysical Journal 755 (August 20, 2012): 132; Dave Waltham and Lewis Dartnell, “Is the Earth Special?” Astronomy & Geophysics 53 (August 2012): 4.25–4.29; Dorian S. Abbot, Nicolas B. Cowan, and Fred J. Ciesla, “Indication of Insensitivity of Planetary Weathering Behavior and Habitable Zone to Surface Land Fraction,” Astrophysical Journal 756 (September 10, 2012): 178; Kevin Heng and Pushkar Kopparla, “On the Stability of Super-Earth Atmospheres,” Astrophysical Journal 754 (July 20, 2012): 60.
2. J. A. Harrison et al., “Global Importance, Patterns, and Controls of Dissolved Silica Retention in Lakes and Reservoirs,” Global Biogeochemical Cycles 26 (June 30, 2012): GB2037; Eric Struyf et al., “The Global Biogeochemical Silicon Cycle,” Silicon 1 (October 2009): 207–13; Daniel J. Conley, “Terrestrial Ecosystems and the Global Biogeochemical Silica Cycle,” Global Biogeochemical Cycles 16 (December 6, 2002): 1121; Philippe Van Cappellen, Suvasis Dixit, and Justus van Beusekom, “Biogenic Silica Dissolution in the Oceans: Reconciling Experimental and Field-Based Dissolution Rates,” Global Biogeochemical Cycles 16 (November 7, 2002): 1075; Haewon Park and William H. Schlesinger, “Global Biogeochemical Cycle of Boron,” Global Biogeochemical Cycles (November 5, 2002): 1072.
3. Floor Vandevenne et al., “Agricultural Silica Harvest: Have Humans Created a New Loop in the Global Silica Cycle?” Frontiers in Ecology and the Environment 10 (June 2012): 243–48.